For M&M, what I said above applies. No better cards than what's on their site. Keep in mind the biz card also has twice the annual fee - 33,000 miles as long as you have enough in your account (or 110 euros otherwise). That means, unless you're SEN who gets it for free, you need to spend 33,000 euros with the card every year just to make up for the annual fee!

IMO AmEx isn't worth it either. Acceptance in Germany is even worse than in the US. Many place still don't take any credit cards and if they do, usually it's only Visa and MC.

Not a credit card, but one option to look into is Payback, sort of a cross-brand loyalty program. Earn points for shopping in certain stores and convert them 1:1 onto miles:
https://www.payback.de/pb/milesandmore/id/45080/

Payback also offers a credit card that lets you collect 2 Euros = 1 point outside of the partner brands, but it's an AmEx, so yea ... meh